package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.security.PublicKey;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Slf4j
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private ISeckillVoucherService seckillVoucherService;

    @Resource
    private RedisIdWorker redisIdWorker;

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private RedissonClient redissonClient;

    //创建线程安全的有界阻塞队列支持在队列为空时，消费者线程等待（阻塞），在队列满时，生产者线程等待（阻塞）。
    //生产者线程（例如处理用户请求的线程）可以将下单任务放入队列，消费者线程（例如后台工作线程）可以从队列中取出任务异步处理。
//    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);

    //创建一个只有一个线程的线程池
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    //加载lua脚本
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;

    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    private IVoucherOrderService proxy;

    @PostConstruct
    private void init() {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }

    private class VoucherOrderHandler implements Runnable {
        String queueName = "stream.orders";

        @Override
        public void run() {
            while (true) {
                try {
                    //1.获取消息队列中的订单信息
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queueName, ReadOffset.lastConsumed())
                    );
                    //判断是否获取成功
                    if (list == null || list.isEmpty()) {
                        //如果获取失败说明没有消息，继续下一次循环
                        continue;
                    }
                    //没有进入if说明获取到了消息，就要进行解析
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> value = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
                    //2.完成下单
                    handleVoucherOrder(voucherOrder);
                    //ACK确认
                    stringRedisTemplate.opsForStream().acknowledge(queueName, "g1", record.getId());
                } catch (Exception e) {
                    log.error("订单处理异常", e);
                    handlePendingList();
                }
            }
        }

        //异常处理信息
        private void handlePendingList() {
            while (true) {
                try {
                    //1.获取pending-list中的订单信息
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create(queueName, ReadOffset.from("0"))
                    );
                    //判断是否获取成功
                    if (list == null || list.isEmpty()) {
                        //如果获取失败说明pending没有异常消息，结束循环
                        break;
                    }
                    //没有进入if说明获取到了消息，就要进行解析
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> value = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
                    //2.完成下单
                    handleVoucherOrder(voucherOrder);
                    //ACK确认
                    stringRedisTemplate.opsForStream().acknowledge(queueName, "g1", record.getId());
                } catch (Exception e) {
                    log.error("处理pending-list订单异常", e);
                    try {
                        Thread.sleep(20);
                    } catch (InterruptedException ex) {
                        throw new RuntimeException(ex);
                    }
                }
            }
        }
    }



    //创建订单函数
    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        //1.获取用户id
        Long id = voucherOrder.getVoucherId();
        //2.创建锁对象
        RLock lock = redissonClient.getLock("lock:order:" + id);
        //3.获取锁
        boolean isLook = lock.tryLock();
        //4.判断锁是否成功
        if (!isLook) {
            //获取锁失败
            //在多线程并发的情况下避免重试，应该直接返回错误信息，而不是重新调用
            log.error("获取锁失败，返回错误");
            return;
        }
        try {
            //获取代理对象（事务）
            proxy.createVoucherOrder(voucherOrder);
        } finally {
            //释放锁
            lock.unlock();
        }
    }

    /**
     * 秒杀优惠券
     *
     * @param voucherId 优惠券id
     * @return 订单id
     */
    public Result seckillVoucher(Long voucherId) {
        //获取用户
        Long userId = UserHolder.getUser().getId();
        //生成订单id
        long orderId = redisIdWorker.nextId("order");
        //1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString(),
                String.valueOf(orderId)
        );
        //判断结果是否为0
        int r = result.intValue();
        if (r != 0) {
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        return Result.ok(orderId);
    }

    /**
     * 创建订单
     *
     * @param voucherOrder
     * @return
     */
    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        //一人一单
        Long id = voucherOrder.getId();
        int count = query().eq("user_id", id).eq("voucher_id", voucherOrder.getVoucherId()).count();
        if (count > 0) {
            log.error("用户已经购买过一次");
            return;
        }
        //5.扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1")
                .eq("voucher_id", voucherOrder.getVoucherId())
                .gt("stock", 0)
                .update();
        if (!success) {
            log.error("库存不足");
            return;
        }
        save(voucherOrder);
    }


    //    private class VoucherOrderHandler implements Runnable{
//        @Override
//        public void run() {
//            while ( true){
//                try {
//                    //1.获取队列中的订单信息
//                    VoucherOrder voucherOrder = orderTasks.take();
//                    //2.创建订单
//                    handleVoucherOrder(voucherOrder);
//                } catch (InterruptedException e) {
//                    log.error("订单处理异常", e);
//                }
//
//            }
//        }
//    }


//    @Override
//    public Result seckillVoucher(Long voucherId) {
//        //获取用户
//        Long userId = UserHolder.getUser().getId();
//        //1.执行lua脚本
//        Long result = stringRedisTemplate.execute(
//                SECKILL_SCRIPT,
//                Collections.emptyList(),
//                voucherId.toString(), userId.toString()
//        );
//        //判断结果是否为0
//        int r = result.intValue();
//        if (r != 0){
//            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
//        }
//        //为0，又购买资格，把下单信息保存到阻塞队列
//        //创建订单
//        VoucherOrder voucherOrder = new VoucherOrder();
//        //生成订单id
//        long orderId = redisIdWorker.nextId("order");
//        voucherOrder.setId(orderId);
//        //用户id
//        voucherOrder.setUserId(userId);
//        //代金券id
//        voucherOrder.setVoucherId(voucherId);
//        //放入阻塞队列
//        orderTasks.add(voucherOrder);
//        proxy = (IVoucherOrderService) AopContext.currentProxy();
//        return Result.ok(orderId);
//    }

//    @Override
//    public Result seckillVoucher(Long voucherId) {
//        //1. 查询优惠券
//        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
//        //2.判断秒杀是否开始
//        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
//            return Result.fail("秒杀尚未开始");
//        }
//
//        //3.判断秒杀是否结束
//        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
//            return Result.fail("秒杀已经结束");
//        }
//
//        //4.判断库存是否充足
//
//        if (voucher.getStock() < 1) {
//            return Result.fail("库存不足");
//        }
//
//        Long id = UserHolder.getUser().getId();
//        //5.创建锁对象
//        //SimpleRedisLock Lock = new SimpleRedisLock("lock:order:" + id, stringRedisTemplate);
//        RLock lock = redissonClient.getLock("lock:order:" + id);
//        boolean isLook = lock.tryLock();
//        if (!isLook) {
//            //获取锁失败
//            //在多线程并发的情况下避免重试，应该直接返回错误信息，而不是重新调用
//            return Result.fail("请勿重复下单");
//        }
//        try {
//            //获取代理对象（事务）
//            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
//            return proxy.createVoucherOrder(voucherId);
//        } finally {
//            //释放锁
//            lock.unlock();
//        }
//    }

}

